The present invention relates to coating compositions having one or more enhanced properties. In particular, this invention relates to water-borne thermoplastic and thermosetting resin coating compositions and to water-reducible or water-dispersible thermoplastic resin coating compositions which provide coatings which have enhanced gloss properties.
Coating compositions, e.g., paints, can be divided into at least four (4) different categories. Thus, the coating composition can be a water-borne thermoplastic resin composition, often called a thermoplastic emulsion. Alternately, the coating composition can be a water-borne thermosetting resin composition, often called a thermosetting emulsion. The third type of coating composition is a water-reducible or water-dispersible thermoplastic resin composition. Finally, the coating composition can be a water-reducible or water-dispersible thermosetting resin composition. These water-reducible or water-dispersible compositions include solvent (other than water)-borne compositions.
These four (4) different types of coating compositions are substantially different from each other, e.g., in composition, and in application utility and procedure. For example, the thermoplastic resins are present substantially in their final form in the coating composition, while the thermosetting resins are not, and often require elevated temperatures to form the final crosslinked or thermoset resin. The thermoplastic and thermosetting emulsions include resins which have very little or no significant water solubility. On the other hand, the water-reducible or water-dispersible compositions include resins which have substantial water solubility.
In many instances with all four (4) types of coating compositions, the gloss of the final coating is an important consideration. High coating gloss, indicative of the reflective nature of the coating, is often desired, e.g., for aesthetic reasons. Thus, it would be advantageous to provide coating compositions which have enhanced gloss properties.
The use of 2-hydroxyethyl ethylene urea as a reactive diluent in water-reducible and water-dispersible thermosetting resin coating compositions is known. Such component acts to effectively increase the weight solids, reduces the viscosity of aqueous industrial baking coatings crosslinked with amino resins, such as melamine/formaldehyde resins, and functions as a cosolvent in the liquid coating, reducing viscosity and solvating polymeric components. During the stoving cure step, 2-hydroxyethyl ethylene urea reacts with the amino resin and becomes part of the coating, and thus reduces the volatile organic compounds (VOC) in the coating composition.
Heretofore, the use of 2-hydroxyethyl ethylene urea has not been recognized as providing gloss enhancement in any coating composition. Moreover, this component has not been used in any coating composition other than water-reducible and water-dispersible thermosetting resin coating compositions, e.g., as discussed above.